Are Cold Cuts Safe? What to Know About the Recent Listeria Outbreaks

Recently, Boar’s Head issued a nationwide recall of its ready-to-eat liverwurst products produced between June 11 and July 17, 2024, along with any of its then-unexpired deli products, due to a listeria outbreak. As of early September, nine deaths and nearly 60 illnesses and hospitalizations across 18 states were linked to the outbreak, making many wonder if deli meats are safe to eat and what symptoms to watch out for.

“Listeria can lead to a bacterial infection called listeriosis that most commonly causes GI [gastrointestinal] illness,” says Marwan Azar, MD, a Yale Medicine infectious diseases expert. But, he warns, it can lead to more serious illness, hospitalization, and even death in vulnerable people.

Listeria, the common name for Listeria monocytogenes (or L. monocytogenes), is a bacterium that can infect certain types of food, including raw vegetables (especially sprouts), fresh fruits (especially melons), raw meat, unpasteurized milk products, and certain processed meats and cheeses.

Raw vegetables may become infected with the bacteria through contaminated soil or manure used as fertilizer. Raw meat, unpasteurized milk products, soft cheeses, and ready-to-eat deli meats might acquire the bacteria through the milk or tissue of an infected animal. Or these food products might come into contact with the bacteria at any time along the journey from processing to plate, through contaminated equipment in a processing plant, or the hands or equipment of anyone who handles the food along the way.

The outbreak in Boar’s Head meats, first identified in August, was more recently traced back to a plant in Jarratt, VA. Genetic sequencing tests tied a strain of listeria detected in Boar’s Head liverwurst to the bacteria found in people who died or became sick, according to the Centers for Disease Control and Prevention (CDC). The company first recalled its liverwurst products, then expanded the recall to more than 3,500 tons of meat, including ham and other items. Now, the plant has been closed indefinitely. The company also said it had identified liverwurst processing as the source of contamination and would permanently discontinue the product.

Below, Dr. Azar answers commonly asked questions about listeria-related illness.

L. monocytogenes can be especially hard to kill because it hides inside the cells of the people and animals it infects.

“By hiding inside the cells, the bacteria escape many of the immune system’s approaches to eradicating it and preventing it from multiplying,” Dr. Azar explains.

The bacteria are also impervious to cold temperatures. They survive under refrigeration, freezing, and other food preservation measures. In fact, the bacteria not only stay active but continue to multiply unchecked in cold storage.

Not everyone who eats food contaminated with listeria will get sick with listeriosis. For those who do, symptoms usually show up later, typically in a week or two, but they could come in as little as a few days or appear three months later.

“Most people will just have the same gastrointestinal symptoms typically seen in food poisoning, like nausea, vomiting, diarrhea, and abdominal pain,” says Dr. Azar. “But with listeriosis, unlike food poisoning, those GI symptoms can present with more flu-like symptoms, like fever, chills, and muscle aches.”

Listeriosis can cause more serious problems, too, especially for older adults, pregnant women, and others who have a weakened immune system because of a health condition or medicines they might take. “The most feared manifestation is a central nervous system infection, such as meningitis or encephalitis,” Dr. Azar says.

Encephalitis is an inflammation of the brain tissue; meningitis is an inflammation of the protective membranes covering the brain and spinal cord. Both are usually caused by a bacterial or viral infection and can lead to serious complications or even death if not treated promptly.

Either one of these central nervous system complications can happen when the bacterial infection spreads beyond the gut and into other body systems, such as the spinal cord and brain.

Central nervous system symptoms of listeriosis can include a headache, stiff neck, fatigue, and sensitivity to light. People might also feel confused or less alert. Or, they could have trouble with balance and even experience convulsions.

In extremely rare cases, listeriosis can inflame the lining of the abdomen, or the peritoneum—a condition called peritonitis. “It’s an infection of the intra-abdominal space, which can lead to abdominal pain and sometimes fluid buildup in the abdomen, but this is less common,” Dr. Azar says.

In most healthy people, a listeria infection may be so mild that it goes unnoticed. However, in vulnerable people with weaker immune systems, when the body doesn’t fight off the infection, it can spread—for instance, to the central nervous system as described above—worsen, and, if left untreated, lead to death.

Anyone can get listeriosis, but you’re at greater risk of severe illness, hospitalization, and death if you are over age 65, have an immune-suppressing condition, or take immune-suppressing medications. Some commonly prescribed medicines that tamp down the immune system include corticosteroids, given for asthma, eczema, and other conditions; biologics, used for arthritis, Crohn’s disease, and other autoimmune diseases; and calcineurin inhibitors, mTOR inhibitors, and other medications for organ transplant recipients.

Pregnant women and their fetuses face serious risks, too. In a pregnant woman, listeriosis can cause miscarriage, premature birth, or stillbirth. A baby (or fetus) can also become infected by the mother. (Listeria is not otherwise contagious from person to person.)

Most people will only get the GI symptoms of listeriosis and will probably feel better in a few days without any treatment. “Still, if you know or suspect you’ve eaten food contaminated with listeria and are experiencing symptoms—no matter how mild they may be—see a doctor,” says Dr. Azar.

A doctor can make sure you don’t have a bloodstream infection that could lead to more serious illness, such as a central nervous system infection, Dr. Azar explains.

“They can at least stay in close contact with you to monitor for the development of more concerning signs and symptoms, such as a fever,” he adds. “So, if, two days later, you develop a fever, a plan would be in place.”

In fact, if your GI symptoms come with a fever, that’s a sign to call your health care provider, too. “Many of the transient GI bugs or standard foodborne illnesses, like common viruses or E. coli, do not present with a fever,” Dr. Azar says. “A fever should raise an eyebrow that you have more than a transient viral illness.”

If your symptoms are getting worse rather than better after 24 hours or you're feeling more pain than seems normal for a GI bug, these are red flags, too, he adds.

“Of course, if you have any signs of meningitis, like an intractable headache, neck pain, neck stiffness, confusion, and/or light sensitivity, those would be reasons to seek immediate care,” he says.

It’s especially important for pregnant women to check with a health provider if they have any symptoms that suggest listeria, since the condition can threaten the pregnancy if not treated.

For relatively mild GI symptoms, over-the-counter medications for diarrhea, vomiting, and pain are often enough. Doctors treat more serious infections with antibiotics, especially in infants, pregnant women, and people over age 65. Central nervous system listeriosis infections could require up to six weeks of IV antibiotics in the hospital, Dr. Azar adds.

While listeria contamination can withstand cold temperatures, it can’t withstand proper cooking. Basic safety and hygiene in your kitchen can help.

Everyone should:

• Wash their hands with soap and warm water before preparing, serving, or eating food.

• Wash and scrub fruits and vegetables with a clean produce brush that is washed with dish detergent after each use.

• Cook food thoroughly to a safe internal temperature.

People who are at risk of serious illness from listeria should take additional precautions, including not eating certain types of food, such as unpasteurized milk or dairy products. The CDC provides a more detailed list of preventive measures.

This latest spate of listeria infections adds to the estimated 30 U.S.-based listeria outbreaks recorded in the last decade. Evidence suggests cases may be on the rise. Research is ongoing to understand why.